The last time that Apple allowed the public to obtain beta versions of an operating system was in 2000, when it charged $29.95 for the privilege of running an early edition of what became OS X 10.0, better known as Cheetah. Since then, only registered developers -- who pay $99 annually -- have been able to retrieve unreleased copies of its desktop OS.

The sign-up process for what Apple called the "OS X Beta Seed Program" requires only an active Apple ID and there's no charge or eligibility requirements to enter the program other than agreeing to a long terms-and-conditions document ( download PDF).

However, those terms legally muzzle participants from disclosing anything related to the beta, just as registered developers are prohibited from sharing what they know about Apple's pre-release software.

"You agree that you will not disclose, publish, or otherwise disseminate any Confidential Information to anyone other than individuals who are enrolled in the same individual seed as you, or as otherwise expressly permitted or agreed to in writing by Apple," the terms and conditions stated. "Accordingly, you agree that Apple will have the right to seek immediate injunctive relief to enforce obligations under this Agreement in addition to any other rights and remedies it may have."

In an accompanying FAQ that Apple also published Tuesday, it said the same in much plainer English. "Don't blog, post screen shots, tweet or publicly post information about the pre-release Apple software, and don't discuss the pre-release Apple software with or demonstrate it to others who are not in the OS X Beta Seed Program," the FAQ said.

Although the warnings were stock in the software industry, it is unlikely that Apple will be able to keep a lid on interesting information users glean from the betas, if only because of the number expected to enroll.

But with the move, Apple has followed Microsoft, and a host of other software developers, in providing betas to the general public. In 2012, for example, Microsoft made several pre-release versions of Windows 8 available to millions of customers.

By refusing to do so, Apple has left itself open to criticism that it doesn't widely test its software before release. Such brickbats have often been thrown at Apple after customers discover bugs, instability issues or fringe problems in new editions of OS X and iOS.

To gather feedback, Apple will install a "Feedback Assistant" in the Dock of the OS X 10.9.3 beta; the application will be used to send both feedback and diagnostic files to Apple.

Apple said nothing about extending the program beyond Mavericks, so it was unclear whether the next edition -- which Apple will likely unveil June 2 on the opening day of its Worldwide Developers Conference (WWDC) -- will also be covered, and thus available to the public before a final release, probably in October.

That edition of OS X, which will be named, like Mavericks, after a California locale, will be available to registered developers between WWDC and release.

Customers who rely on the Beta Seed Program can update to the final, production-quality version when it ships, Apple said in the FAQ. Those who want to retreat from a beta must reinstall the latest shipping version of OS X, then restore applications, documents and other files from a backup.